Modern Chemistry & Applications

Fe-zeolites as hybrid adsorbents catalysts for siloxane removal in biogas upgrading

Joint Event on 19^th International Conference on Medicinal Chemistry & Multi Targeted Drug Delivery & International Conference on Catalysis and Pyrolysis

November 05-06, 2018 | San Francisco, USA

Alba Cabrera Codony, Eric Santos Clotas and Maria J Martin

University of Girona, Spain

Scientific Tracks Abstracts: Mod Chem Appl

Abstract:

Different types of both natural and synthetic zeolites, covering a wide range of physical and chemical properties, were evaluated as adsorbents/catalyst for siloxane removal in lab-scale adsorption tests of siloxane D4. Wet oxidation processes were used for the regeneration of the spent zeolite samples, including ozonation and Fenton-like treatment. The results on the uptake of gaseous D4 by various zeolites led to the conclusion that BEA type materials presented the highest catalytic activity for the siloxane ring-opening and formation of ?-??-silanediols due to the high content of Bronsted and Lewis acidic sites. Those silanediols formed on the BEA surface were detached from the catalytic acidic sites when water was available and was narrow enough to diffuse into the channels, enhancing the removal efficiency for D4. The water-soluble ?-??-silanediols formed by catalytic the activity of iron exchanged Fe-BEA type zeolites during D4 adsorption were easily removed by wet regeneration treatment with water, however, regeneration was incomplete. Adding H2O2 in a heterogeneous Fenton-like regeneration treatment led to a complete recovery of the adsorption capacity of the zeolite sample. On successive adsorption/regeneration cycles, the recyclability of the zeolites catalyst was hampered by the accumulation of carbonaceous materials, which caused a loss of the catalytic activity, affecting both the adsorption and the regeneration stages. Bronsted and Lewis acidic sites promoted D4 transformation into silanediols, which was the fundamental step that rules D4 uptake. At the same time, iron exchanged in Fe-BEA zeolites promoted the catalytic activity towards Fenton-like reactions for the regeneration of the exhausted materials.

Biography :

Alba Cabrera Codony graduated in Environmental Sciences in 2010 for the University of Girona and defended her PhD dissertation at the same university of 2016 within the Laboratory of Chemical and Environmental Engineering research group. She has her expertise in environmental applications of adsorption and advanced oxidation processes. Her main research focus was oriented to biogas upgrading, studying the removal of siloxanes through adsorption and the catalytic regeneration of exhausted activated carbons and inorganic materials.

E-mail: alba.cabrera@udg.ed